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Old 10-12-2013, 01:05 PM
 
1 posts, read 1,416 times
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To be honest with you, you were better to trade or sell this car before you did anything to it, such as trying to repair your A/C when you have an engine using a quart of oil every 800 miles, and an automobile that has other issues as you have stated. Your wife may like the car and it's looks, and that is OK but unless she is willing to spend the bucks to keep and maintain the car for herself then perhaps she would consider another newer Jetta and enjoy the looks of the NEW car. I realize that there is a cost to contend with here but if you have to have a car for your basic transportation then there will always be costs incurred. I have older vehicles as I run a truck and do not really need a new car, however I have the knowledge to perform major repairs and have the equipment to do so. If you want to learn about these different types of repairs to automobiles then start with something older that may be simple to repair and build your knowledge and equipment from there, or take courses at your local community college to enhance your knowledge as well as networking with other car guys.
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Old 03-13-2017, 02:18 PM
 
2 posts, read 1,434 times
Reputation: 10
if I replace the drier and the compressor on my 1999 dodge durango 5.2 liter will the new oil be sucked out when I pull a vacuum on the system prior to use?
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Old 03-13-2017, 02:23 PM
 
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it may depend on the vacuum pump used.Do you know if it is a stage 2 pump? This could possibly make a difference. I would definately ask Auto Zone personnel(That is if you are renting one) I know I would unless you do a/c work on a regular basis
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Old 03-13-2017, 04:39 PM
 
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The answer is no....the oil will remain in the system.
But....why are you asking a question and then answering it a few minutes later?
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Old 03-13-2017, 07:58 PM
 
Location: Tip of the Sphere. Just the tip.
4,540 posts, read 2,739,305 times
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Way too many half-truths and misinformation out there about air conditioning.

If you're replacing a compressor due to an internal mechanical failure- and this is on an R134A system with a multi-path condenser- you HAVE to replace the condenser. Sure you could flush out the old R-12 condensers because they were single-path- but that's just not true with most R134-A systems.

And not only do you have to replace the condenser (because metal fragments and such and thrown out by a failing compressor)- you ALSO have to remove the expansion valve and flush the lines. You CAN'T flush through the expansion valve- that won't work. Also you *must* replace the drier particularly if it's on the high pressure side (a low pressure side accumulator is debatable... but your best bet is a new one).

Now, if you're replacing a compressor because it was merely leaking... you can skip much of that. But if it came apart internally... these steps are not negotiable. Sure people get away with skipping steps once in a while- but they're rolling the dice and the odds are not in their favor.

Ok, about compressor oil: Every a/c system has a specific oil capacity- you need to find this. Should be in a manual- sometimes it's even on the sticker. After operating a while, this oil will be spread throughout the system... so you can only guesstimate how much is in any given component (including the compressor).

Now... compressors *should* come with a tag on them telling you precisely what type of oil is in them, and how much. I say 'should' because this is best practice... but lots of aftermarket companies don't bother. If that's the case- then you just have to consider it an unknown. Most a/c compressors will have a drain plug. So just drain *all* the oil out of it and throw it away unless you *know* what kind and how much is in there. Also turn the clutch a few times and drain any that comes out the discharge side.

So at this point, you should know how much oil the system requires- and how much is in the compressor (which may be zero if you just drained it). If you have just flushed the entire system (which is best-practice), then you know there's no oil in the system. So add the whole system capacity to the system when you reassemble. Put maybe half into the compressor and half into the DISCHARGE (not suction) line. If the compressor came with a known type and amount of oil... you may have to add a little additional to the discharge line to bring the whole system up to total capacity.

If you're doing this without a total system flush... then you're just guesstimating. This can be done... but it's easy to get wrong if you don't have much experience. The rule of thumb most mechanics use is to assume that there will be about 2 ounces in each (non-flushed) component (compressor, condenser, evaporator)... so let's say you didn't flush the system but you're replacing the compressor. By this rule you'd assume that there are 2 ounces in the condenser and 2 in the evaporator... so make sure there is (system capacity)-4 ounces in the compressor. It's NOT a precise way to do things, and you're taking a risk- it's unavoidable. I err on the side of caution... I'd rather have a couple ounces too much oil than a couple ounces too little. But this is how it's generally done in a shop.

Your best bet though is to always go with *known* quantities. This means that you replace the condenser if necessary. Flush the entire system. Replace the drier or accumulator. KNOW how much and what type of oil is in the compressor. Add oil as necessary to reach the KNOWN capacity of the system. Then evacuate and charge with refrigerant by weight- not by pressure. This pretty much guarantees that the system will work well. There are many shortcuts you can take in this process- and experienced people do it all the time. But you're introducing risk and uncertainty... so I don't recommend shortcuts for shade-tree mechanics.*






*This is not meant to be derogatory. I respect and encourage shade-tree mechanics. But there *is* a difference in skill level between a professional and a shade-tree... and this is not to be ignored.

Last edited by turkey-head; 03-13-2017 at 08:08 PM..
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